Ship based gas transport system

ABSTRACT

A gas storage system formed of a continuous pipe wound in plural layers, each layer having plural loops. The pipe may be distributed within a container, which may serve as a carousel for winding the pipe and as a gas containment device. When containers, each containing a continuous pipe are stacked upon each other, the weight of upper containers may be born by the walls of lower containers, thus preventing lower layers of pipe from suffering stresses due to crushing by upper layers. A method of transporting gas to a gas distribution facility including obtaining a supply of gas at a gas supply point remote from the gas distribution facility, injecting the gas into a continuous pipe bent to form plural layers, each layer including plural loops of pipe, transporting the continuous pipe along with the gas to the gas distribution facility preferably in a ship and discharging the gas at the gas distribution facility. It is preferred that cooling of the pipe during discharging of the gas be conserved so that during subsequent filling the pipe is initially cool. Also, in a further aspect of the invention, during filling, the gas pressure should be maintained as constant as possible for example by controlled release of an incompressible liquid from the pipe as the pipe is filled with gas. Energy from the incompressible liquid may then be recovered or dissipated outside of the pipes.

This is a continuation-in-part application of U.S. patent applicationSer. No. 08/550,080 filed Oct. 30, 1995 now abandoned.

FIELD OF THE INVENTION

This invention relates to apparatus and methods for the transport andstorage of fluids; more particularly, this invention relates to thetransport and storage of compressed gases such as natural gas.

BACKGROUND OF THE INVENTION

In the parent application a ship based gas transportation system inwhich a plurality of cylinders are organized into cells of 3 to 30cylinders per cell was also disclosed. A manifold and valve system wasdescribed for connecting the cylinders to on shore loading andoff-loading terminals.

The amount of equipment and the complexity of the inter-connection ofthe manifolding and valving system in the ship based gas transportationsystem bears a direct relation to the number of individual cylinderscarried onboard the transport ship. Accordingly, in large ships there isa significant expense associated with the manifolding and valvingconnecting the gas cylinders. Thus, the need has arisen to find astorage system for compressed gas that can both contain largerquantities of compressed gas and simplify the system of complexmanifolds and valves.

SUMMARY OF THE INVENTION

A gas storage system, particularly adapted for transportation of largequantities of compressed gas on board a ship, includes a large storagevolume provided by coils of substantially continuous pipe. The use oflong lengths of continuous pipe for gas storage leads to a significantlyreduced cost as less interconnecting equipment is required between gasstorage containers.

There is therefore provided, in accordance with the present invention, agas storage system formed of a continuous pipe. The continuous pipe ispreferably packed or coiled into a container. In one aspect of theinvention, the continuous pipe is wound in plural layers, each layerhaving plural loops. The continuous pipe, however, may be distributedwithin a container in a variety of configurations. The container for thecoiled pipe may serve several functions. First, the container may act asa carousel for winding the pipe. Second, the container may serve as ameans for lifting the pipe. Third, the container may serve as a gascontainment device for the atmosphere surrounding the continuous pipe.

When containers, each containing a continuous pipe, are stacked uponeach other the weight of upper containers may be born by the walls oflower containers, thus preventing the lower layers of pipe from havingto withstand the crushing forces from the weight of the upper layers ofpipe, with the resulting induced stresses that reduce the acceptable gaspressure values.

In accordance with a further aspect of the invention, there is provideda method of transporting gas to a gas distribution facility includingobtaining a supply of gas at a gas supply point remote from the gasdistribution facility, injecting the gas into a continuous pipe bent toform plural layers, each layer including plural loops of pipe,transporting the continuous pipe along with the gas to the gasdistribution facility preferably in a ship and discharging the gas atthe gas distribution facility. It is preferred that cooling of thecontinuous pipe storage system during discharging at the gasdistribution facility be conserved in the gas storage system so thatduring subsequent filling at the gas supply point the continuous pipe isinitially cool.

The transported gas may be cooled during discharging by reducingpressure of the gas adiabatically, circulating a storable fluid againstthe flow of the gas in a heat exchanger and then circulating thestorable fluid into the continuous pipe gas storage system.

Cold in the gas may be preserved by piping the cold gas through a heatexchanger against, for example, a flow of sea water, and then storingthe chilled sea water on the ship. Gas being filled into the continuouspipe storage system at a gas supply point may then be cooled using thecooled sea water.

The gas storage system of the present invention which uses continuouspipe wound to largely fill an enclosed volume has several advantages.First, the pipe diameter may be made smaller than 12 inches, thusincreasing fracture toughness and decreasing the probability andseverity of failure. Second, the technology for the continuousproduction of lengths of pipe is well known, particularly in the oilindustry, thereby facilitating production of the continuous pipe. Third,complicating design features such as large domes, typically welded tothe ends of cylinders are not required. Fourth, fewer control valves,pressure relief valves and related equipment are required whencontinuous pipe is used as compared to using many cylinders. This leadsto a reduction in cost. Fifth, the use of continuous lengths ofrelatively small diameter pipe may also permit more cold to be retainedin the pipe steel after the gas is discharged, as compared with largerdiameter cylinders. This retention of cold in the pipe steel facilitatesre-filling the continuous pipe storage system with gas of the gas supplypoint.

These and other aspects of the invention are described in the detaileddescription of the invention and claimed in the claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

There will now be described preferred embodiments of the invention, withreference to the drawings, by way of illustration only and not with theintention of limiting the scope of the invention, in which like numeralsdenote like elements and in which:

FIG. 1 shows an exemplary coiled continuous pipe gas storage systemaccording to the invention adapted for the transportation of gas byship;

FIG. 2A is a perspective view of a continuous pipe coiled in accordancewith a first embodiment of the invention;

FIG. 2B is a perspective view of a continuous pipe gas storage system inaccordance with a second embodiment of the invention;

FIG. 3 is a perspective view, partly in section, showing continuous pipewound in a container according to an embodiment of the invention, anddemonstrating both cubic and hexagonal packing;

FIG. 4 is a plan view of continuous pipe wound with minimum radius turnsto fill a rectangular container;

FIG. 5 is a perspective view of continuous pipe in U-shaped loops lyingback to back to form a single layer;

FIG. 6 is a plan view of a ship, partly cut away, with spool containerscontaining continuous pipe, in which the containers are oriented withvertical axes and are packed in a cubic pattern between transversebulkheads;

FIG. 7 is a plan view of a ship, partly cut away, with spool containerscontaining continuous pipe, in which the containers are oriented withvertical axes and are packed in a hexagonal pattern withinsemi-hexagonal bulkheads;

FIG. 8 is a plan view of a ship with hexagonally packed containers withthree rows of containers within semi-hexagonal bulkheads;

FIG. 9 is a cross-section through five spool containers stacked uponeach other with continuous pipe wound around the spool (not all thepipes are shown);

FIG. 10 is a top plan view of the base of a container in accordance withone embodiment of the invention;

FIG. 10A is a section through a container for use in accordance with theinvention;

FIG. 11A is a radial section through the base of the container of FIG.11;

FIG. 11B is a section through the base of a container perpendicular tothe section of FIG. 11A;

FIG. 11C is a radial view of the base of the container of FIG. 10;

FIG. 12 is a side elevation view of a side wall of the container of FIG.10; and

FIG. 13 is a schematic of a system for the conservation of cold in gasdischarged from, for example, a ship.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A loop of pipe is defined herein to mean a length of pipe that turnsback on itself, so that fluids travelling within the pipe turn more than90°. A layer of pipe is defined herein to mean a set of pipes that arespaced laterally from each other and that occupy a band whose thicknessis approximately equal to the diameter of one of the pipes. Inoperation, a layer may be horizontal, vertical or at any angle therebetween.

It is understood that the material employed to make the continuous pipeused in practising the invention will be ductile and not brittle atoperational fluid transport pressures and temperatures, and that thematerial is impervious to gas stored within the continuous pipe. It willalso be understood that while very long lengths of pipe are ideal, itmay be necessary to make intermediate connections between long pipesections to facilitate manufacturing. The continuous pipe may befabricated from any normal grade of steel, for example X70, but the pipesteel may also be quenched and tempered for increased strength after allwelding is complete. Alternatively, the continuous pipe may also bewrapped with high tensile steel wire.

An exemplary gas storage device 11 is shown in FIG. 3. Multiple gasstorage devices 11 are shown in FIG. 1.

The gas storage device 11 of the present invention is made bydistributing or coiling a continuous pipe 10 within a container 12 inplural layers, each layer being formed of plural loops of pipe. Anyopenings in the continuous pipe 10 that allow flow of gas into or out ofthe pipe 10, such as at the ends of the pipe 17, 19, are provided withvalves, for example, valves 21 in FIG. 1. The valves allow thecontinuous pipe 10 to be sealed for the storage and transportation ofgas. Each length of pipe 10 should also be provided with a pressuresafety valve (not shown) to allow release of gas over a preset pressure.

The container 12 has a base 14, an outer containment side wall 16, aninner containment side wall 18 and a top 20. The inner containment sidewall 18 forms a central core, when the container is shaped in the formof a spool. The container 12 may also provide a carousel function,namely it may provide a support into which the continuous pipe 10 may bewound and then lifted, thus making the pipe easier to handle and load,for example in a ship. In addition, the container 12 distributes theload of the continuous pipe 10 to the outside walls of underlyingcontainers 12, such as the stack of containers 12 illustrated in FIG. 9,in which the weight of the continuous pipe 10 is born by the side walls16 and 18.

Ends 17, 19 of the continuous pipe 10 preferably extend through a gastight aperture in the interior wall 18 of the container 12. As shown inFIG. 1 vertical pipes 23A may be connected to the ends 17 of thecontinuous pipe 10 to connect them to high, medium or low pressuremanifolds 25A, 25B, 25C respectively for charging the continuous pipe 10with gas at a gas supply point and discharging gas from the continuouspipe 10 at a gas distribution facility. The manifolds 25A, 25B and 25Care preferably on the deck 63 of a ship, while the containers 12 arestored in the hold. Valves 27 on the pipes 23A may be used for controlof the flow of gas from the manifolds 25A-25C to and from the continuouspipes 10. Vertical pipes 23B may be connected to the ends 19 to connectthem to high and low pressure fluid lines 29A and 29B. Valves 31 onlines 23B may be used to control fluid flow into and out of thecontinuous pipes 10. Alternatively, the ends 17, 19 may extend throughthe exterior wall 16 of the container 12 instead of through the interiorwall 18.

The base 14, side walls 16 and 18 and top 20 of the container 12 arepreferably sealed so as to be air tight. This air tight seal providesthe container 12 with a containment function in relation to fluidscarried by the continuous pipe 10 or the container 12 or both. Thecontainer 12 may also be filled with a supporting matrix of material,such as a dry inert powder, a cement, a liquid, such as water, or aconventional mud such as is used in drilling wells. The supportingmatrix material may have a specific gravity greater than 1, to assist insupporting the load of the continuous pipe 10. Filling the container 12with a supporting matrix may be particularly advantageous where thespecific gravity of the pipe and stored gas combination is about equalto the specific gravity of the supporting matrix. In this instance, morelayers of continuous pipe 10 may be stacked upon each other withoutincreasing the risk of exceptional stresses on the inside walls of thecontinuous pipe.

Alternately, in cases where the continuous pipe 10 does not needsupport, the container 12 may be filled with a dry inert gas such asnitrogen, air or exhaust gases. Preferably, a fan or like means (notshown) can be provided to circulate the atmosphere within the container12 by means of ducting (not shown) which enters and exits the container12 via sealed apertures (not shown). It is also preferable that theatmosphere in the container 12 be periodically tested for the presenceof escaping gas.

For example, acoustic monitors may also be placed in the containers 12.Such acoustic monitors will sense either the noise made by the leakinggas or the sound of the crystalline metal in the continuous pipe 10 if afault occurs and subsequently grows in the pipe steel. In addition, theatmosphere within the container and external to the continuous pipe 10may be sniffed with commonly available sniffing equipment to detect thepresence of leaking gas.

It is believed that leaks in the continuous pipe 10 will start small.Once detected, the affected coil of the continuous pipe 10 will bepromptly emptied and the leak repaired. Should the leak grow rapidly toa significant size, the pressure will rise inside the container 12. Thewalls of the container 12, for example, the upper wall of the centralcore, should be provided with conventional rupture disks or collapsiblepanels 33, set to open before the pressure inside the container 12reaches a level where it might damage some other part of the walls ofthe container 12. The gas flow from such a rapid leak will then beconducted away by ventilation ducts 35 and vented via a chimney ofapproved height. It is believed that such double containment ofpressurized gas will be, and also be recognized by regulatory agencies,as exceedingly safe so that lower values for the safety factor of thepipe relative to bursting may be used with regulatory approval.

Referring now to FIG. 2A, the continuous pipe may be coiled on the base14 of the container 12 in alternating layers from the outside to theinside and from the inside to the outside. Layer 11A in FIG. 2A iscoiled from the inside to the outside, while layer 11B is coiled fromthe outside to the inside on top of layer 11A. In this manner, thecontinuous pipe 10 can be installed in the container 12 by winding thepipe around the central core defined by the inner wall 18, preferablybeginning with the inside and ending at the outside. Many layers ofcontinuous pipe 10 may be wound on the core as the lower layers of pipe10 are capable of supporting the upper layers of pipe without the riskof the pipe 10 suffering significantly increased stress in addition tothat due to the internal pressure of pressurized gas. The maximum numberof layers of pipe that may be supported on any given layer of pipe isreadily found from pipe strength calculations. As an example, a 6 inchoutside diameter pipe may be wound in a 40 ft wide container about 10feet high, hence with about 20 layers and about 30 loops (each loopconsisting in this case of one 360° loop of pipe), resulting in a lengthof continuous pipe in the order of 9 miles. The central core may be inthe order of 10 ft wide for a 6 inch pipe. Pipe outside diameters ofbetween 1 inch and 10 inches are preferred. The size of the inner coreof the container 12 depends on the minimum bend of the pipe, which inturn depends on the temperature at which the continuous pipe is bent andthe material from which the continuous pipe is made. For example, coldbending of continuous pipe made from X70 welded plate steel results inabout a 10 D (diameter of pipe) minimum radius. Hot bending may reducethe minimum radius to 3 D.

Winding continuous pipe in the manner shown in FIG. 2A results inpartial cubic and partial hexagonal packing as shown in FIG. 3, whichshows a section through the layers of continuous pipe. In cubic packing,each pipe section abuts four other pipe sections, one above, one belowand one on each side. In cubic packing the pipe 10 fills about 78.5% ofthe space in the container 12. In hexagonal packing, each pipe sectionhas six point contact with adjacent pipe. This results in anapproximately 90.7% space fill of the container 12. Hexagonal packing issuperior to cubic packing both in terms of space filling and in terms ofreducing the effect of transverse crushing forces on the circumferentialstress of lower parts of the pipe 10. In the case of the coil shown inFIGS. 1 and 3, perfectly cubic and perfectly hexagonal packing occursalong lines at 90° to each other. If the axes of perfect hexagonalpacking are rotated slowly around the coil, then it is believed possibleto obtain an average packing density of about 84.6%.

As shown in the embodiment in FIG. 2A if the axis of the coil isvertically oriented in use, it can be assured that fluids in thecontinuous pipe 10 will drain to one end of the pipe, for example end 13shown. The base 14 of the container 12 need not be flat but may beraised or lowered in the center, for example to form either a pyramidalor conical shape to facilitate drainage of fluids from the continuouspipe. In the case of a raised central portion of the base 14 of thecontainer 12, the valved end of the pipe 10 should be at the outside ofthe container 12.

In the embodiment shown in FIG. B, the pipe 10 is wound on a core 22.Winding proceeds axially from one end plate 24 to the other end plate26. This forms a reel type of winding. The core 22 and end plates 24 and26 together form a support for the continuous pipe 10. The same windingconsiderations apply to the embodiment of FIG. 2B as for FIG. A.

In the embodiment of FIG. 4, straight sections 32 alternate with bends34 to form in this case a square, but rectangles, hexagons or otherpolygonal shapes could also be formed. The same winding considerationsapply as for the embodiment of FIG. 2A. Such an embodiment could be usedto fill the entire hold of a ship. However, a configuration withstraight and bent sections is harder to wind, and thus is preferred whenjustified by significantly improved packing of coils in the ship's hold.

Perfect hexagonal packing may be obtained with pipe distributed within,for example, a rectangular container, such as the hold of a ship, in themanner shown in FIG. 5. Each layer of pipe 42 is formed of loops 44 thatare U-shaped, with straight sections 46 alternating with bends 48. Thepipe is thinned at the bends by rolling the pipe in conventional mannerand then bending it into 180° bends. Additional layers may be formed inthe manner illustrated by end 49 of the continuous pipe which overliesthe underlying layer in a hexagonal packing pattern. End 47 is flangedto receive a valve (not shown). While this embodiment has the advantageof hexagonal packing, gas flow will be restricted in the continuous pipeat the bends, making a preferred embodiment when charging anddischarging of gas into the continuous pipe is desired to be at arelatively slow rate.

Continuous pipe wound in a container with a coil, as for example shownin FIG. 2A, where the coil has a vertical axis, may be transported in ahold 60 of a ship 62 as shown in FIGS. 6, 7 and 8. A ship's hold may be,for example, about 100 ft wide and 700 ft long, and is preferably sealedwith a controlled atmosphere, similar to the sealing of the containers12. The containers 12 may be side by side in a cubic pattern as shown inFIG. 6. This results in space utilization of about 75.4% fortwenty-eight 50 ft. diameter containers 12. The containers 12 may alsobe arranged in a two row or three row hexagonal pattern as shown inFIGS. 7 and 8. The holds 60 in FIGS. 7 and 8 respectively are separatedby hexagonal bulkheads 64, 66. In FIG. 7, the space utilization fortwenty six 53.6 ft. containers is about 81.25% and in FIG. 8 for fiftyseven 36.603 ft. diameter containers is about 79.81%. Preferably, thecontainers 12 will be stacked in the ship's hold as shown in FIG. 9, forexample with a stack of five containers 12 each about 11 ft high to atotal height of about 55 ft. The total height of the stack of containers12 is limited by considerations of ship stability. Alternatively, thecontainers 12 may be oriented with their axes horizontal. In a furtheralternative, the ship's hold may be contoured to form a cylindrical basein which a coil or coils having a horizontal axis parallel to the ship'slongitudinal axis may be rested. While a single coil extending thelength of the ship may be advantageous, it may be difficult for someshipyards to install. Installing several smaller coils connectedserially, each comprising several layers and having a horizontal axis,may be easier for some shipyards to manage without damaging thecontinuous pipe 10.

The containers 12 are preferably stacked, such that there are forexample about five containers 12 stacked as illustrated in FIG. 9, withwalls 16, 18 of lower containers 12 supporting the upper containers. Thecontainers 12 may be constructed in any of various ways, so long as theyare capable of supporting and containing the continuous pipe 10. Asillustrated in FIGS. 10-12, the container 12 may be formed of 24vertical columns 52 on the inside and 24 vertical columns 53 on theoutside, the outside vertical columns 53 being topped with a box ringbeam 54 and spaced at 36 inch center to center spacings. The base orfloor 14 of the container 12 is supported by 24 I-beams 56 covered withplates 58. The I-beams 56 connect respective ones of the inner columns52 and the outer columns 53. As an example, the outer columns 53 may beformed of a 12×4 web with 8×6 flanges, with the inner columns 52 havingslightly smaller flanges. The floor I-beams 56 may have a 12×3 web and8×7 flanges. The walls 16, 18 and floor 14 are covered with flat plates58, 59 and sealed so as to be impervious to fluid in the container. Thecontainers 12 so formed are preferably provided with a lid 20 as shownin FIG. 3, and sealed during operation. Except for the top container,the lid of the next lower container 12 may be provided by the base ofthe container 12 above.

Where multiple continuous pipes 10 are transported together, they may beconnected together serially such that all of the continuous pipes 10 ina ship's hold, for example, may be circulated with gas at the same timeand such that a pig may be run through them in one pass for inspectionand cleaning services. The continuous pipes 10 in the ship's hold may beprovided with a controlled atmosphere and with insulated walls.

When transport is completed, the continuous pipes 10 in a ship's holdmay then be connected to an on-shore or off-shore buoy terminal by high,intermediate and low pressure manifolds 25A, 25B and 25C (FIG. 1) asalso described in co-pending application Ser. No. 08/550,080 filed Oct.30, 1995, the content of which is herein incorporated by reference.

Gas being supplied to the pipes 10 may be refrigerated before beingpumped into the continuous pipes 10. For cold transportation, it ispreferred that the containers 12 be insulated with insulation 41 appliedto all external walls of the containers 12.

For use in transporting gas, for example natural gas, from a gas supplypoint, for example an on shore terminal or an off-shore buoy, to adistant gas distribution facility, for example another on shore terminalor an offshore buoy, a gas supply must first be provided at the gassupply point. For example, gas could be transported to the on-shore oroff-shore gas supply point by a pipeline. The gas is then compressedinto the continuous pipes 10, and, for example, stacked in a ship 62 asshown in FIGS. 6, 7 or 8 through manifolds 25A, 25B and 25C (FIG. 1) ata pressure for example of about 3000 psi. This pressure could be ramped,for example from 800 psi to 1500 psi and then from 1500 psi to 3000 psito make compression more efficient. The continuous pipes 10 are thentransported, for example by the ship 62, to the distant gas distributionfacility, where the gas is discharged through the manifolds 25A, 25B and25C.

Preferably, the gas is discharged at the gas distribution facility in amanner that cools the continuous pipe 10. This may be achieved, forexample, by allowing the gas to expand out of the pipes 10, in a rollingprocedure in which a first pipe 10 is emptied, initially through thehigh pressure manifold 25A, then the medium pressure manifold 25B andthen the low pressure manifold 25C. When the first pipe 10 is emptyingthrough the medium pressure manifold 25B, the next pipe 10 may beemptied through the high pressure manifold 25B, and so on until allpipes 10 are emptied. The expansion of the gas in the continuous pipes10 cools the continuous pipe, for example down to 0° F., but not lowerthan the temperature at which the pipe itself becomes brittle. Thecooled pipe may then be transported back to the remote gas supply pointto charge the pipes again with gas. Since the pipes are already cooled,a greater weight of gas may be charged while filling the pipes at thegas supply point to a given pressure. For maximal advantage from thismanner of operation, the pipes 10, containers 12 and the ship's hold 60may be covered with insulation 41. Cooling of the continuous pipe 10 maybe enhanced by dropping the pressure in a heat exchanger on the deck ofthe ship against either inert gas which can be circulated through thecontainers 12 but outside the pipes 10, or medium pressure gas which canbe expanded and circulated through the continuous pipes 10 which alreadyhave been emptied. In addition, refrigeration may be used to cool thegas before injection into the continuous pipes 10.

Gas in the continuous pipes 10 may be discharged by injecting anon-corrosive non-aqueous incompressible fluid that is not miscible withthe gas (for example a liquid hydrocarbon having more than about 7carbon atoms in the case of natural gas storage and transportation) atone end of the continuous pipe 10 and forcing gas out of the other end.Such a liquid may be stored in a liquid storage container 80 and forcedinto the pipes 10 through high and low pressure fluid supply lines 29Aand 29B using pump 82. The storage container 80 may be connected vialine 81 to augment the ship's fuel supply (not shown) since after usethe fluid will contain dissolved gas which will come out of the solutioninside the container 80.

In a similar manner, the pipes 10 may be charged by filling the pipewith a high pressure gas at one end from for example the manifold 25Aand pushing the incompressible liquid out of the pipes 10 at the otherend at a constant pressure. The pushed pressurized liquid may then bepassed through an energy removal unit 86 such as a turbine to generateelectricity or refrigeration on a line 88 controlled by valve 90connecting the high and low pressure fluid supply lines 29A and 29B, andthen used for filling the next in a series of continuous pipes 10 byinjecting it into the bottom of the next pipe. Once filling of thecontinuous pipes 10 is completed, the liquid is returned via line 29Aand line 84 to the liquid storage container 80. When filling the pipe 10it is first filled with an incompressible liquid. The continuous outflowof the incompressible liquid should be regulated with valves, forexample valves 31, and the energy removal unit 86 to maintain theincoming gas approximately constant pressure, thus avoiding unnecessaryheat gain due to the expansion and recompression of the gas whilefilling the continuous pipe 10.

During discharging of the gas at the gas distribution facility, when thegas is first discharged, it may be discharged through the high pressureline 25A to shore (in direction A). End B of the lines 25A, 25B and 25Cmay be connected to other containers 12 in other holds of the ship. Apart of the high pressure gas in line 25A may be directed through valve43 and heat exchanger 72 to medium pressure line 25B. The gasadiabatically reduces pressure through the heat exchanger 72 and cools.In addition, a part of the high pressure gas from line 25A may berecirculated back to the continuous pipes 10 through valve 45, the heatexchanger 72, line 51 and line 29A without a reduction in pressure.However, as the gas directed from the high pressure line 25A to line 25Bis reduced in pressure, with a drop for example in the order of 1500psi, it cools the gas directed back to the continuous pipes 10 throughthe heat exchanger 72. This cooling may be substantial, and may cool thegas to -50° F. or lower. As the pressure drops in the pipes, the lines25A, 25B and 25C may be sequentially selected to discharge the gas fromthe pipes. After cooling, the ship 62 may return to the gas supply pointloading facility for another load of gas, with the pipes 10 remainingcold.

It is expected that by cooling the continuous pipes 10 with cold gasfrom the heat exchanger 72, the continuous pipes 10 on the returnjourney will have a temperature in the order of -50° F. After loadingthe pipes 10 with gas, and returning to the discharge point, thetemperature of the gas in the pipes 10 will increase to about 0° F. Itis desirable to recover this cold from the gas during discharge of thegas at the gas distribution facility. For that purpose, referring toFIG. 13, as the gas is being discharged from the continuous pipes 10through lines 25A, 25B or 25C and ship-to-shore connections usingon-shore compressors 90 the gas is piped through a heat exchanger 92against a flow, preferably countercurrent, of a suitable transportablefluid such as sea water. The sea water is pumped through the heatexchanger 92 with for example a pump 94. During discharge of the gas,the sea water is pumped from the sea at 93 through the heat exchanger 92and line 95 into storage tanks on board the ship, which may for examplebe insulated ballast tanks 96 located within the double hull or doublebottom of the ship. In this way, the sea water is cooled, but not to thepoint at which ice is formed, and forms a store of high heat capacitycold fluid. During subsequent filling of the pipes 10 at the loadingfacility, again using on-shore compressors, the cold sea water may bepumped from the ballast tanks 96 through the heat exchanger 92 and backto the sea, thus cooling any gas flowing through the lines 25A, 25B and25C into the pipes 10. A ship may carry in the order of 17,000 tons ofgas for the loaded voyage to the gas distribution facility, and maycarry in its ballast tanks 10,000-15,000 tons of cooled sea water on thereturn voyage back to the gas supply point.

This aspect of the invention may be used particularly advantageouslywith the continuous pipe coils 10, but may also be used with other gasstorage containers, such as straight cylinders as disclosed in our priorpatent application. A cold gas storage container in this context means acontainer whose temperature is below ambient temperatures (thetemperature of the air through which the vehicle, for example the ship,moves), but is preferably much lower than ambient temperatures. Inaddition, where large volumes of gas are being transported by land, thetechnique may also be used in principle, although the cold storage fluidmay, in that instance, be some other fluid such as ordinary water.

Ships used for the transport of gas according to this invention shouldbe double hulled and meet all safety requirements for the transportationof hazardous material.

It is expected that, for the transport of natural gas, about 95% of thegas can be discharged while reducing the pressure in the continuouspipes 10 to about 150 psi. This amount of gas provides a heel or supplyof un-discharged gas which may be used as fuel for the ship's engines onthe next leg of the ship's voyage back to the gas supply point.

Any safely transportable gas may be transported with the gas storagedevice of the invention, such as natural gas, town gas, chlorine,hydrogen, oxygen, nitrogen, argon, ethane and ethylene.

In a further embodiment, the storage device of the invention may beplaced within a barge and moored close by a city together with acompressor and connected to a major gas supply pipeline to provide gassupply during hours of peak demand. During periods of low demand, thestorage device may be replenished. The storage device could also beplaced in a building on land or underground to provide a similarfunction, for example for the storage of natural gas for an electricpower plant or town gas for a city. In smaller sizes, the storage deviceof the invention could be used to store compressed natural gas (CNG) ina CNG fuelling station for vehicles.

Having now disclosed the invention, it is understood that a personskilled in the art could make modifications to the disclosed inventionwithout departing from the essence of the invention that is covered bythe scope and meaning of the claims that follow.

We claim:
 1. A compressed gas storage apparatus comprising:a plurality of pipe coils, each of said pipe coils comprising a substantially continuous pipe coiled in plural layers, each of said plural layers including plural loops of said pipe; valve means adapted for selective flow connection to a source of compressed gas; and means for flow connecting each of said pipe coils to said valve means, whereby compressed gas may be received through said valve means, stored in said plurality of coils and subsequently discharged from said plurality of coils through said valve means.
 2. The apparatus according to claim 1 comprising additionally a plurality of support structures for said pipe coils, each said support structure being adapted to contain and support at least one said pipe coil and to permit stacking of said support structures and the pipe coils therein.
 3. The apparatus according to claim 2 wherein each said support structure has a substantially central core and said at least one pipe coil contained therein is wound about said substantially central core.
 4. The apparatus according to claim 2 wherein said support structures comprise gas tight containers, including top, bottom and side wall portions.
 5. The apparatus according to claim 2 wherein said plural support structures are stacked upon each other.
 6. The apparatus according to claim 1 wherein said pipe coils are carried by one of a vessel and a vehicle.
 7. The apparatus according to claim 1 wherein said pipe coils are carried in the hold of a vessel.
 8. The apparatus according to claim 7 wherein said hold of said vessel is adapted to be made gas tight and comprising additionally:means for supplying inert gas to said hold for maintaining an inert atmosphere within said hold in surrounding relationship to said pipe coils; and pressure relief means for venting the hold of said vessel to atmosphere.
 9. The apparatus according to claim 7 wherein said hold of said vessel is insulated.
 10. A compressed gas storage apparatus comprising:a substantially gas tight container having top, bottom and side wall portions; a substantially continuous pipe coiled within said container in plural layers, each of said plural layers including plural loops of said pipe, said substantially continuous coiled pipe occupying a major portion of the interior of said container; means for flow connecting said coiled pipe to a source of compressed gas external to said container; and pressure relief means associated with said container for automatically venting said container to atmosphere in the event pressure inside said container and external to said coiled pipe exceeds a preselected limit whereby any gas leaking from said coiled pipe will be contained in said container and vented to atmosphere.
 11. The apparatus according to claim 10 comprising additionally valve means associated with said coiled pipe for controlling the flow of compressed gas between said source of compressed gas and said coiled pipe.
 12. The apparatus according to claim 10 comprising additionally a supporting matrix in said container adapted to at least partially support the weight of said pipe coiled within said container.
 13. The apparatus according to claim 12 wherein said supporting matrix is a liquid.
 14. The apparatus according to claim 10 comprising additionally means for providing an inert gas atmosphere in said container.
 15. The apparatus according to claim 10 wherein said container is carried by one of a vessel and a vehicle.
 16. The apparatus according to claim 10 wherein said container is a hold of a vessel.
 17. The apparatus according to claim 16 wherein said hold of said vessel is insulated.
 18. A system for compressed gas transport comprising:a vessel; a plurality of compressed gas storage cells constructed and arranged to be transported by said vessel, each of said compressed gas storage cells comprising a pipe coil formed from a substantially continuous pipe coiled in plural layers, each of said plural layers including plural loops of said pipe; a first manifold, said first manifold including means adapted for flow connection to a terminal; flow connection means for connecting each of said compressed gas storage cells to said first manifold; and valve means for selectively controlling the flow of compressed gas between said compressed gas storage cells and said first manifold, whereby said compressed gas storage cells selectively may be flow connected to said first manifold and said first manifold may be flow connected to said terminal.
 19. The apparatus according to claim 18 comprising additionally a second manifold, said second manifold including means adapted for flow connection to said terminal and wherein said flow connection means and said valve means are adapted to cooperate additionally with said second manifold, whereby said compressed gas storage cells selectively may be flow connected to each of said first and second manifolds.
 20. The apparatus according to claim 18 comprising additionally a source of pressurized liquid, means for flow connecting each of said pipe coils to said source of pressurized liquid, and valve means for selectively controlling the flow of pressurized liquid between said source of pressurized liquid and each of said pipe coils, whereby pressurized liquid may be used to fill said pipe coils of said compressed gas storage cells as compressed gas is evacuated therefrom and may be displaced from said pipe coils as pressurized gas is added thereto, thereby limiting the expansion of gas in said pipe coils as compressed gas is removed therefrom and added thereto.
 21. The apparatus according to claim 18 comprising additionally:heat exchanger means having first and second flow paths therethrough; an insulated tank for containing a heat transfer fluid; means for selectively flow connecting said insulated tank to one of said first and second flow paths through said heat exchanger; and means for selectively flow connecting said first manifold to the other of said first and second flow paths of said heat exchanger, whereby compressed gas evacuated from said compressed gas storage cells can be circulated through said heat exchanger to chill said heat transfer fluid and said chilled heat transfer fluid then may be stored in said insulated tank and subsequently used to chill compressed gas being supplied to said compressed gas storage cells.
 22. The apparatus according to claim 18 Wherein said compressed gas storage cells comprise additionally an gas tight container for each of said pipe coils.
 23. A compressed gas storage apparatus comprising:a pipe coil formed from a substantially continuous pipe coiled in plural layers, each of said plural layers including plural loops of said pipe, said pipe coil having a first end and a second end; valve means associated with one of said first and second ends of said pipe coil and adapted for selective flow connection to a source of compressed gas; a container adapted to contain a liquid substantially immiscible with the compressed gas to be stored in said compressed gas storage apparatus; means for flow connecting the other of said first and second ends of said pipe coil to said container; and valve means for selectively controlling the flow of liquid between said container and said pipe coil, whereby as compressed gas is evacuated from one end of said pipe coil, said liquid can be added to the other end of said pipe coil and as compressed gas is added to one end of said pipe coil, said liquid can be removed from said other end of said pipe coil, thereby limiting the expansion of said compressed gas in said pipe coil as compressed gas is removed therefrom and added thereto.
 24. The apparatus according to claim 23 wherein said gas is natural gas and said liquid is a liquid hydrocarbon.
 25. The apparatus according to claim 1, 10, 18 or 23 wherein each of said layers of pipe is formed of a substantially continuous spiral of pipe wound in one substantially radial direction to form a coil of pipe.
 26. The apparatus according to claim 1, 10, 18 or 23 wherein said substantially continuous pipe is oriented and arranged so that liquid drains to one end thereof.
 27. The apparatus according to claim 1, 10, 18 or 23 wherein said substantially continuous pipe is coiled in a substantially hexagonal cross sectional pattern.
 28. The apparatus according to claim 1, 10, 18 or 23 wherein said substantially continuous pipe is coiled in a substantially cubic cross sectional pattern.
 29. The apparatus according to claim 1, 10, 18 or 23 in which each of said loops of pipe is formed in a series of substantially u-shaped sections, each of said connected substantially u-shaped sections having a bend between straight sections thereof.
 30. The apparatus according to claim 1, 10, 18 or 23 wherein said substantially continuous pipe has a substantially uniform internal diameter and is adapted to be inspected internally by means of a pumpable pipe pig.
 31. The apparatus according to claim 1, 10, 18 or 23 wherein said substantially continuous pipe has an external diameter greater than one inch and an internal diameter of less than ten inches.
 32. The apparatus according to claim 1, 10, 18 or 23 in which said layers of pipe abut each other.
 33. The apparatus according to claim 1, 10, 18 or 23 in which said loops of pipe abut each other.
 34. The apparatus according to claim 1 or 23 wherein a plurality of said coils of substantially continuous pipe are connected together serially.
 35. The apparatus according to claim 1 or 23 wherein a plurality of said coils of substantially continuous pipe are connected to a common manifold.
 36. The system according to claim 7, 16 or 18 comprising additionally a loading terminal for supplying compressed gas to said vessel for storage in said substantially continuous pipe coils.
 37. The system according to claim 7, 16 or 18 comprising additionally an unloading terminal for receiving compressed gas from said substantially continuous pipe coils.
 38. The apparatus according to claim 19 wherein said first manifold comprises a high pressure manifold and said second manifold comprises a low pressure manifold. 